Hydraulic hammers are generally known to include a tool extending partially out of a housing. Such hammers may include a hydraulically actuated power cell having an impact system operatively coupled to the tool. The impact system generates repeated, longitudinally directed forces against a proximal end of the tool disposed inside the housing. The distal end of the tool, extending outside of the housing, may be positioned against rock, stone, or other materials, thereby to break up those materials. During operation, the hydraulic hammer will form large pieces of broken material as well as stone dust and fine grit. The stone dust may include abrasive material, such as quartz, which could increase wear and cause premature failure of components should it migrate along the tool and into the interior of the hydraulic hammer.
Various seal arrangements have been proposed to address the issue of migrating dust. In many of these devices, the seal is positioned centrally within the housing, near the internal components of the power cell. Locating the seal in this manner, however, makes it difficult and overly time-consuming to repair and/or replace, as the housing and internal components must be at least partially disassembled to access the seal. The seal is a consumable wear component, and therefore the down time and resources needed to maintain a centrally located seal can be significant.
While locating the seal closer to the distal end of the housing may improve access and facilitate replacement, such a seal location increases the likelihood that the seal will be impacted by debris during operation. To improve sealing engagement between the seal and the tool, the seal is typically formed of a relatively soft, flexible material. Impacts from debris may tear, rip, or otherwise damage the seal so that it no longer adequately prevents migration of dust along the tool.
U.S. Pat. No. 5,873,579 to Prokop discloses a hydraulic hammer having a seal located near the distal end of the housing and a separate, distally positioned transverse slide member for limiting direct access to the seal. The slide member is retained in a chamber sized to permit the slide member to move transversely with respect to the tool axis, thereby to accommodate swivel motion of the tool during operation. The slide member and its retaining structure, however, must be removed in order to repair and/or replace the seal, thereby increasing the complexity and cost of maintaining the device. In an alternative embodiment, Prokop discloses a sealing ring disposed on an inner wall of the slide member to provide additional sealing. The sealing ring, however, is directly exposed to the debris generated during operation, and the slide member and retaining structure must still be removed to access the primary inner seal.